Need advise on a property occupied with mental disability tenants

[Kano Wu]

I am interested in a property which is currently using as a residential program for people with mental disabilities.

The numbers looks good, great cash flow. Catholic Charities pay the owner each month, but they don't have any kind of written agreement which is my main concern. The owner has a property manager visiting the house in a daily base and check out the tenants. He said the property manager would like to continue working with the new owner and I don't need to do anything after I take over the property. 

I am very hesitated to take over because I don’t know what kind of liability I might have and what kind of problem I might face.Do I need any extra insurance to protect my investment?

Has anyone deal with this situation before?

Thanks!